Jan.
16, 2007 — NOAA National
Centers for Coastal Ocean Science scientists, along with colleagues
from the National Institute of Standards and Technology, Medical University
of South Carolina and College of Charleston have identified that it
is metal-mediated free radical production that transform Pfiesteria
piscicida and Pfiesteria Shumway from harmless dinoflagellates into
toxic organisms that can cause estuarine fish kills. These free radicals
are activated chemicals produced as a by-product of biological activity.
(Click NOAA image for larger view of harmful algal bloom in
Lake Erie taken on Sept. 15, 2006. Click
here for high resolution version. Please credit “NOAA.”)

"NOAA
is committed to supporting the research needed to find answers to the
Pfiesteria puzzle," said retired Navy Vice Admiral Conrad
C. Lautenbacher, Jr., Ph.D., undersecretary of commerce for oceans
and atmosphere and NOAA administrator. "The economic impact of
harmful algal blooms in the United States averages $49 million yearly,
but individual outbreaks can be extremely costly. The 1997 Pfiesteria
bloom in Chesapeake Bay cost the Maryland seafood and recreational fishing
industries almost $50 million in just a few months."

The team,
led by Peter Moeller, Ph.D., of the NOAA
Center for Coastal Environmental Health and Biomolecular Research
in Charleston, S.C., identified new components, with emphasis on heavy
metals, contributing to Pfiesteria toxin mortalities in certain estuarine
fish species. The experiments were designed to isolate key components
that lead to mortality in these fish.

Laboratory
experiments were performed using sheepshead minnows—a species
found in brackish conditions and tolerant of low-oxygenated water that
may otherwise be inhospitable to other fish species. The experiments
utilized variations in temperature, Pfiesteria bacteria, heavy metals
commonly found in estuaries, brackish water and natural light.

Moeller's
collaborators at the National Institute of Standards and Technology
and the Medical University of South Carolina were able to characterize
the metal-containing toxin using five distinct instrumental methods:
nuclear resonance spectroscopy; inductively coupled plasma mass spectrometry;
liquid chromatography particle beam glow discharge mass spectrometry;
electron paramagnetic resonance spectroscopy, and x-ray absorption spectroscopy.
The results showed that the high toxicity of the metal-containing toxins
is due to metal-mediated free radical production.

This activity
can explain Pfiesteria's toxicity, as well as the previously reported
difficulty in observing the molecular target due to the ephemeral nature
of radical species. These findings represent the first formal isolation
and characterization of a radical forming toxic organic-ligated metal
complex from an estuarine/marine dinoflagellate.

The findings
add an increased understanding of how metals, commonly found in the
estuarine and marine environment, interact with the biological systems
in the environment and how those interactions potentially impact both
marine animals and human health.

The discovery
may not only help solve one of the more intriguing scientific puzzles
of the 1990s but may also lead to a new way at looking at the toxicity
of harmful algal blooms. These blooms are increasing globally and threatening
human and marine health, as well as having significant economic impacts.

Moeller's
team made the discovery after noting previous scientific research into
the presence of free metallic radicals in the formation of toxins in
other harmful algal blooms, including research that dates back to the
1920s.

"We
found in looking at the literature as far back as the 1920s, that in
previous research that it was the presence of a series of compounds
and factors in most cases where there was a triggered toxicity of the
organism," said Moeller. "We developed a hypothesis that heavy
metals were the key compounds and that when combined with exposure to
light and other environmental cues, they cause the formation of a toxin.
Once those precise variables change the toxin disappears."

Pfiesteria,
originally identified in 1988 by North Carolina researchers JoAnn Burkholder
and Ed Noga and characterized with assistance from Florida researcher
Karen Steidinger, is believed to be the source of significant fish kills
in the mid-Atlantic region, particularly in the Neuse River in North
Carolina and the Chesapeake Bay's estuary systems during the mid-1990s.

Although
it killed significant numbers of fish, it was determined that consuming
fish affected by the toxin was not harmful to humans. It was, however,
identified as a source of respiratory and skin rashes among fishers
in the areas at the time of the fish mortality events.

NOAA, an
agency of the U.S. Commerce Department,
is celebrating 200 years
of science and service to the nation. From the establishment of
the Survey of the Coast in 1807 by Thomas Jefferson to the formation
of the Weather Bureau and the Bureau of Commercial Fisheries in the
1870s, much of America's scientific heritage is rooted in NOAA. NOAA
is dedicated to enhancing economic security and national safety through
the prediction and research of weather and climate-related events and
information service delivery for transportation, and by providing environmental
stewardship of the nation's coastal and marine resources. Through the
emerging Global Earth Observation System of Systems (GEOSS),
NOAA is working with its federal partners, more than 60 countries and
the European Commission to develop a global monitoring network that
is as integrated as the planet it observes, predicts and protects.